Evaluating Intrahepatic and Intraperitoneal Sodium Pentobarbital or Ethanol for Mouse Euthanasia

Area of Science:

• Veterinary Medicine
• Animal Welfare
• Research Methodology

Background:

• Intraperitoneal (IP) injection of sodium pentobarbital (PB) is a common method for mouse euthanasia.
• However, IP PB has drawbacks, including potential pain and misinjection.
• Alternative methods are needed to improve the efficiency and humaneness of mouse euthanasia.

Purpose of the Study:

• To compare the efficacy of intrahepatic (IH) versus IP injection of PB for mouse euthanasia.
• To evaluate IP ethanol (ET) as an alternative euthanasia agent.
• To assess the impact of isoflurane anesthesia on euthanasia outcomes.

Main Methods:

• Eighty mice were randomized into six groups, receiving IP or IH injections of PB or ET, with or without isoflurane anesthesia.
• Key variables included misinjection rates (necropsy), time to apnea, and time to cessation of heartbeat (CHB).

Main Results:

• The IH PB injection group had a high misinjection rate (93%), precluding its recommendation.
• IP ET resulted in significantly shorter times to apnea and CHB compared to IP PB in non-anesthetized mice.
• Isoflurane anesthesia shortened CHB time for IP PB injections.

Conclusions:

• Intrahepatic injection of PB is not a reliable method for mouse euthanasia due to technical difficulties and high misinjection rates.
• Intraperitoneal ethanol is a viable and potentially superior alternative to IP PB for mouse euthanasia.
• Anesthesia can influence the speed of euthanasia induction with IP injections.